The invention concerns an automatic shuttle valve with a piston that slides back and forth in a bore that extends through a housing, distributing hydraulic fluid from a driving mechanism among at least two driven mechanisms in accordance with how much power each is demanding.
Manually activated shuttle valves for distributing hydraulic fluid are known. Published German Application 1 903 792 discloses an automatic shuttle valve for regulating liquid levels in motor vehicles. Two spring loaded seats are connected by a rocker and respond to different demands for power. The seat that does not demand power keeps the hydraulic circulation system from the driving mechanism to the driven mechanism closed until the same power consumption ratio is again attained in both driven mechanisms. The valve has several precision parts, two pistons, an adjustable rocker, and springs, that must be produced separately, making it expensive to manufacture the valve and necessary to keep a wide range of parts in stock.
The applicant is presently distributing metal, or the like material, plate and strip tearing and prying type rescue equipment under the trademark "Lukas". This rescue equipment may be employed to extract passengers from a wrecked vehicle with jammed doors. One driven mechanism makes an incision in the plate material of the body of the wrecked vehicle. If the incision is not wide enough to remove the victims from the vehicle, another driven mechanism expands the opening. There is often not enough time in an emergency situation to uncouple the incision cutter from the driving mechanism and to attach the expander. It would accordingly be desirable to have both tools mounted and ready at the same time. To operate both mechanisms alternately or simultaneously off the same driving mechanism, however, has always required manual switching from the driving mechanism.